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11/09/2015
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Introduction to Networks v5.1
Chapter 6:
Network Layer
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6.0 Introduction
6.1 Network Layer Protocols
6.2 Routing
6.3 Routers
6.4 Configure a Cisco Router
6.5 Summary
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Upon completion of this section, you should be able to:
• Describe the purpose of the network layer in data communication.
• Explain why the IPv4 protocol requires other layers to provide reliability. (To include: media independent, unreliable, and connectionless.)
• Explain the role of the major header fields in the IPv4 packet.
• Explain the role of the major header fields in the IPv6 packet.
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End to End Transport processes
• Addressing end devices
• Encapsulation
• Routing
• De-encapsulating
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• Version = 0100
• DS = Packet Priority
• TTL = Limits life of Packet
• Protocol = Upper layer protocol such as TCP
• Source IP Address = source of packet
• Destination IP Address = destination of packet
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• IP address depletion
• Internet routing table expansion
• Lack of end-to-end connectivity
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• Increased address space
• Improved packet handling
• Eliminates the need for NAT
4 billion IPv4 addresses
4,000,000,000
340 undecillion IPv6 addresses
340,000,000,000,000,000,000,000,000,000,000,000,000
vs.
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IPv6 has a simplified
header
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IPv6 has a simplified
header
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• Version = 0110
• Traffic Class = Priority
• Flow Label = same flow will receive same handling
• Payload Length = same as total length
• Next Header = Layer 4 Protocol
• Hop Limit = Replaces TTL field
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Upon completion of this section, you should be able to:
• Explain how a host device uses routing tables to direct packets to itself, a local destination, or a default gateway.
• Compare a host routing table to a routing table in a router.
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• Itself
• Local Host
• Remote Host
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• Routes traffic to other networks
• Has a local IP address in the same address range as other hosts on the network
• Can take data in and forward data out
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Route source – Identifies how the network was learned by the router. Destination network – Identifies the destination network and how it was learned.
Outgoing interface – Identifies the exit interface to use to forward a packet toward the final destination.
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Upon completion of this section, you should be able to:
• Describe the common components and interfaces of a router.
• Describe the boot-up process of a Cisco IOS router.
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Routers require:
• Central processing units (CPUs)
• Operating systems (OSs)
Memory consisting of:
• Random-access memory (RAM)
• Read-only memory (ROM)
• Nonvolatile random-access memory (NVRAM)
• Flash
• The Cisco Internetwork Operating System (IOS) is the system software used for most Cisco devices regardless of the size and type of the device.
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RAM uses the following applications and processes:
• IOS and running-config
• Routing table
• ARP cache
• Packet buffering
ROM stores the following:
• Bootup information that provides the startup instructions
• Power-on self-test (POST) that tests all the hardware components
• Limited IOS to provide a backup version of the IOS.
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Two 4 GB flash card slots
Double-wide eHWIC slots eHWIC 0 AUX port
LAN interfaces
USB Ports
Console USB Type B
Console RJ45
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Upon completion of this section, you should be able to:
• Configure initial settings on a Cisco IOS router.
• Configure two active interfaces on a Cisco IOS router.
• Configure devices to use the default gateway.
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• show ip route - Displays the contents of the IPv4 routing table stored in RAM.
• show interfaces -Displays statistics for all interfaces on the device.
• show ip interface -Displays the IPv4 statistics for all interfaces on a router.
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Chapter Objectives:
• Explain how network layer protocols and services support communications across data networks.
• Explain how routers enable end-to-end connectivity in a small to medium-sized business network.
• Explain how devices route traffic in a small to medium-sized business network.
• Configure a router with basic configurations.
Thank you.